There is a long-standing need to be able to remove fat stains effectively. Therefore, any washing method generally aims to remove at least hydrophobic components of the stains. In order then to have the hydrophobic components of the stains absorbed into the washing liquor, a thermodynamically attractive environment for these stains must be provided.
The prior art offers various solutions for this. One method for cleaning and impregnating functional textiles is described in international patent application WO 2006/066986 A1, wherein firstly the textiles are wetted with a so-called short liquor, that is to say a liquor which has a ratio of the weight of the amount of dry textile to the weight of the amount of water of greater than 1:8, and then a predetermined amount of a hydrophobic active substance is flushed by water out of the detergent supply chamber and into the lye container and is brought into contact with the wetted textiles. According to WO 2010/031675, the treatment composition is sprayed onto the pre-wetted laundry load in the form of fine droplets (spray).
WO 2005/003268 discloses a washing method in which the detergent is dispersed in less water than in conventional methods and thus, with a larger ratio of the amount of dry textile to the amount of water, the laundry is brought into contact with a less strongly diluted washing liquor. No special requirements are placed on the detergent formulation itself. The ratio of the weight of the amount of dry laundry to the weight of the amount of water is 1:2 to 4:1.
WO 2013/134168 A discloses a washing method in which, in at least 2 successive sub-washing cycles, the laundry is treated with a more concentrated detergent composition in the first sub-washing cycle than in a second sub-washing cycle. A washing cycle is in this case the time from creation of a washing liquor to removal of the washing liquor from the washing machine. A washing cycle can be divided into sub-washing cycles, wherein the washing liquor is not removed at the end of the first sub-washing cycle but new, additional water is fed into the existing washing liquor at the start of the second cycle. In said document, it is preferred that the first sub-washing cycle lasts longer than the second. No special requirements are placed on the detergent formulation itself.
WO 2012/048911 A discloses a washing method in a washing machine, wherein the cleaning agent and optionally different cleaning agents or components thereof are sprayed into the interior of the washing machine. The method and the control of the machine are such that much less water than in conventional methods is consumed during the cleaning and also during the rinsing. No further requirements are placed on the cleaning agents, apart from the property that they must be sprayable.
It is known that microemulsions are thermodynamically stable emulsions and have extremely low interfacial tensions. The person skilled in the art also knows that, in order to detach soil, the interfacial tension between water and the fat component of the stain must be lowered.
WO 2013/110682 A describes cleaning agents in particular for washing dishes by hand, but also for pretreating laundry, wherein the agents contain 1 to 50% by weight anionic surfactants and 1 to 36% by weight salts and spontaneously form a microemulsion upon contact with oils and/or fats. Also described are microemulsions which contain 1 to 50% by weight anionic surfactants, 1 to 36% by weight salts, 10 to 80% by weight water and 10 to 80% by weight of at least one triglyceride or a mixture of a triglyceride and one or more constituents from the group consisting of waxes, lipids, terpenes, triterpenes and fatty acids. The formation of the microemulsion takes place in situ with the triglycerides or triglyceride-containing mixtures located on the surface to be cleaned.
U.S. Pat. No. 6,121,220 A discloses acidic cleaning agents for hard surfaces, which can be in the form of a microemulsion. Use of such emulsions in a washing machine is not recommended.
Patent applications EP 0160762 A and WO 95/27035 A propose O/W microemulsions as detergents.
In German patent application DE 10129517 A, it is proposed to use microemulsions consisting of water, one or more hydrophobic components and sugar-based nonionic surfactants as spot treatment agents for textiles or for cleaning hard surfaces. The suitability of said microemulsions for use in washing machines is not described.
EP 1371718 A discloses polymeric nanoparticles having a mean particle diameter of 1 to 10 nm, which are suitable as fabric care additives in detergent formulations to improve the properties such as for example softening, crease resistance, soil and stain removal, soil release, color transfer, dye fixing, static control and anti-foam formation. The nanoparticles may be used with silicone compounds in the detergent formulation, or may be functionalized with silicone groups, in order to expand considerably different textile care properties of the preparations.
U.S. Pat. No. 4,655,952 A discloses a cleaning agent for textile surfaces, in particular textile floor coverings and a method for the production thereof. The product contains a powdered, porous carrier of a foamed, plasticized urea formaldehyde hard foam, which is enriched with cleaning agent, and contains a water-containing surfactant on the carrier, wherein the water adheres completely homogeneously in the carrier material.
JP 04241165 A relates to the treatment of a dyed natural fiber material having an appearance similar to that of a stone-washed material while avoiding the drawbacks of the stone-wash treatment, and discloses the treatment of indigo-dyed denim clothing by stirring and washing in water or in an aqueous solution of a detergent under frictional contact with solid rubber balls and contains 10-50% by weight of an abrasive such as MgO having a particle size of 60-200 mesh.
DE 1900002 A discloses solid washing and cleaning agents, surface-active substances, washing, non-surface-active cleaning salts and washing additives which contain polymers of vinyl compounds having a mean particle size of less than 1 mm.
WO 01/71083 A discloses a washing machine which has a drum for accommodating articles to be washed, wherein the drum has at least two rotatable drum sections and a drive, the drum comprises a plurality of different drum modes, including a mode in which the rotatable drum parts are driven in order to bring about a relative rotation between said drum parts. A control unit controls the appliance in order to carry out a plurality of different rinse programs, each washing program having an associated drum mode.
WO 2010/094959 A1 relates to the cleaning of substrates using a solvent-free cleaning system, which requires the use of only small amounts of water. Said document deals very particularly with the cleaning of textile fibers using such a system, and provides a device for use in this connection.
WO 2007/128962 A enables the efficient separation of the substrate from the polymer particles at the end of the cleaning process and describes a design for using two internal drums.
Finally, WO 2011/073062 A discloses bicontinuous microemulsion systems which are suitable as stain pretreatment agents and are capable of dissolving solid and solidified fat stains in the main wash cycle at a neutral pH value.
Users of washing and cleaning processes, both in the private sector and in the industrial sector, are intuitively aware that, for removing high levels of soiling, the use of a concentrated cleaning liquor with subsequent dilution leads to a better cleaning result than immediately using a diluted cleaning solution. There are many examples of this:
1. For washing the hair, shampoo is applied to the hair in concentrated form. Only once the concentrated solution has had time to act is it diluted and rinsed out.
2. For washing very dirty hands, the market offers hand wash products (for example gels or pastes, also liquid soaps) which are rubbed in as concentrates. Dilution takes place only once the cleaning product has intimately mixed with the (oily) dirt. These products are unable to be effective if they are applied in diluted form, for example are added to a sink.3. When washing dishes, for example very greasy pots, the user intuitively applies a few drops of pure dishwashing detergent onto the sponge or directly into the pot. The cleaning result is then better or easier than when the detergent is used in dilute form in the sink.4. In industrial cleaning processes, for example when washing the engine of a car, the dirty (oily) object is first sprayed with a cleaning agent concentrate which, after intimate mixing with the oil in the dirt, is then diluted and removed for example using a pressure washer.
The situation in the case of conventional textile washing is different. Here, the washing liquor is immediately used in relatively high dilution. The advantage in terms of the cleaning performance resulting from the action of a concentrated surfactant solution is not exploited in this case.
Without wishing to be bound to one theory, the colloidal and interface chemistry background of the higher cleaning performance of a concentrated surfactant solution is to be sought in the phase behavior of water/surfactant/oil mixtures and the resulting interfacial tension between the water and oil phases. As shown in DE 102014202990, which has not yet been published, certain surfactant systems at higher concentrations can form W/O emulsions (Winsor II systems). Upon dilution, a three-phase stage comprising a microemulsion, an excess oil phase and an excess water phase will be passed through, which is characterized by an extremely low interfacial tension and thus by a high fat solubilization capability. Upon further dilution, the type of emulsion changes to an O/W emulsion (Winsor I system). A diluted washing liquor is usually in this state.
In the teaching of the aforementioned document, a considerable saving in terms of surfactant has already been achieved by using the Winsor II system instead of a single-phase microemulsion. Of course, the same cleaning performance can also be achieved by a single-phase microemulsion, but then with a much higher input of surfactants.
The proposed agent is a concentrate which, given a certain dilution to a so-called “short liquor,” results in a Winsor II system and thus provides an improved washing performance on fat stains. This Winsor II system can act on the fat stains in an early phase of the washing operation, as a kind of “full-surface pretreatment” with little wetting of the textiles and without the presence of free washing liquor, and can intimately mix with the fat stains. In a later phase of the washing operation, further dilution takes place, passing through the three-phase stage, until a Winsor I system is obtained which serves to rinse away the solubilized fat stain. In terms of the machine, the challenge when implementing this teaching lies in uniformly distributing the small amount of liquid of the “short liquor” onto the textiles in a wash load. In previous prototypes, this short liquor has been sprayed onto the wash load using a spray device. However, such machines are not commercially available.
More recently, however, alternative methods of uniformly applying a small amount of liquid to a textile load have become available. As an example, mention may be made here of polyamide flakes which are characterized by a high soil holding capacity and which are able to distribute a small amount of liquid in the wash load.
The object of the present invention is thus to provide a washing liquor which can be distributed in the form of a short liquor by water-insoluble solid particles.
Another object of the present invention is, by combining these agents, to make a washing operation more efficient, in particular to reduce the water consumption, by using the water-insoluble particles.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.